Bifurcated stent delivery system having retractable sheath

Abstract

An improved catheter assembly and method are provided for treating bifurcated vessels. The catheter assembly of the present invention includes a tubular sheath for restraining dual balloons normally biased apart. Withdrawal of the sheath allows the balloons to separate and deploy intravascular stents in a bifurcated vessel. The catheter assembly also includes the feature of containing two guide wire lumens in a single catheter designed to track over a single wire prior to arrival at the bifurcation, thus preventing wire wrapping and crossing of the wires.

Description

BACKGROUND OF THE INVENTIONThe invention relates to a stent delivery system for use at a bifurcation and, more particularly, a bifurcated stent delivery system having a retractable sheath.Stents conventionally repair blood vessels that are diseased. Stents are generally hollow and cylindrical in shape and have terminal ends that are generally perpendicular to their longitudinal axes. In use, the conventional stent is positioned at the diseased area of a vessel and, after placement, the stent provides an unobstructed pathway for blood flow.Repair of vessels that are diseased at a bifurcation is particularly challenging since the stent must overlay the entire diseased area at the bifurcation, yet not itself compromise blood flow. Therefore, the stent must, without compromising blood flow, overlay the entire circumference of the ostium to a diseased portion and extend to a point within and beyond the diseased portion. Where the stent does not overlay the entire circumference of the ost...

AI Technical Summary

Benefits of technology

The invention provides for a bifurcated stent delivery system having a retractable sheath. The system is designed for repairing a main vessel and a side branch vessel forming a bifurcation, without compromising blood flow in other portions of the bifurcation, thereby allowing access to all portions of the bifurcated vessel should further interventional treatment be necessary. The catheter and the retractable sheath are designed to reduce the likelihood of wire wrapping during the stenting procedure.

In one aspect of the invention, there is provided a stent delivery assembly for treating bifurcated vessels including a dual balloon Y-shaped catheter. The catheter includes a first expandable member and a second expandable member. A first guide wire lumen is provided for receiving a first guide wire. The first guide wire lumen extends through at least a portion of the catheter including the first expandable member. A second guide wire lumen is provided for receiving a second guide wire, the second guide wire lumen extends through at least a portion of the catheter including the second expandable member. A tubular member is provided, wherein the first expandable member and the second expandable member are normally biased apart, but are restrained and held together by the tubular member to provide a low profile during delivery of a Y-shaped stent.

Problems solved by technology

Repair of vessels that are diseased at a bifurcation is particularly challenging since the stent must overlay the entire diseased area at the bifurcation, yet not itself compromise blood flow.

Where the stent does not overlay the entire circumference of the ostium to the diseased portion, the stent fails to completely repair the bifurcated vessel.

Where the stent overlays the entire circumference of the ostium to the diseased portion, yet extends into the junction comprising the bifurcation, the diseased area is repaired, but blood flow may be compromised in other portions of the bifurcation.

Unopposed stent elements may promote lumen compromise during neointimalization and healing, producing restenosis and requiring further procedures.

Moreover, by extending into the junction comprising the bifurcation, the stent may block access to portions of the bifurcated vessel that require performance of further interventional procedures.

Similar problems are encountered when vessels are diseased at their angled origin from the aorta as in the ostium of a right coronary or a vein graft.

In this circumstance, a stent overlaying the entire circumference of the ostium extends back into the aorta, creating problems, including those for repeat catheter access to the vessel involved in further interventional procedures.

Conventional stents are designed to repair areas of blood vessels that are removed from bifurcations and, since a conventional stent generally terminates at right angles to its longitudinal axis, the use of conventional stents in the region of a vessel bifurcation may result in blocking blood flow of a side branch or fail to repair the bifurcation to the fullest extent necessary.

Such a position of the conventional stent results in a bifurcation that is not completely repaired.

In addition to the problems encountered by using the prior art stents to treat bifurcations, the delivery platform for implanting such stents has presented numerous problems.

The drawback with this approach is there is no way to determine or guarantee that the main-vessel stent struts are properly oriented with respect to the side branch or that the appropriate cell has been selected by the wire for dilatation.

The aperture created often does not provide a clear opening and creates a major distortion in the surrounding stent struts.

There is no way to tell if the main-vessel stent struts have been properly oriented and spread apart to provide a clear opening for stenting the side branch vessel.

One of the drawbacks of this approach is that the orientation of the stent elements protruding from the side branch vessel into the main vessel is completely random.

When dilating the main vessel stretching the stent struts is therefore random, leaving the possibility of restricted access, incomplete lumen dilatation, and major stent distortion.

All of the foregoing stent deployment assemblies suffer from the same problems and limitations.

An uncovered flap or fold in the intima or plaque will invite a "snowplow" effect, representing a substantial risk for subacute thrombosis, and the increased risk of the development of restenosis.

Further, where portions of the stent are left unopposed within the lumen, the risk for subacute thrombosis or the development of restenosis again is increased.

The prior art stents and delivery assemblies for treating bifurcations are difficult to use, making successful placement nearly impossible.

Further, even where placement has been successful, the side branch vessel can be "jailed" or covered so that there is impaired access to the stented area for subsequent intervention.

Attempts to bring any device, such as a bifurcated stent on a bifurcated balloon assembly, to a bifurcation over two wires are prone to the problem of wire wrapping.

The resulting wrapping then creates resistance to advancement of the device, thus resulting in failure of deployment.

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